Frequency Versus Duration of Police Patrol Visits for Reducing Crime in Hot Spots: Non-Experimental Findings from the Sacramento Hot Spots Experiment

Abstract

Research Question Was the effect of police patrols reducing crime and disorder in the Sacramento Hot Spots Experiment (SHSE) more strongly associated with the average frequency of patrol visits or the total duration of all visits combined? Data Two independent measures of patrol were used to analyze initial and new data on the 42 hot spots that Telep et al. (2014) studied in 21 matched pairs for the SHSE: Computer-Assisted Dispatch (CAD) records on the number of and duration of patrol visits to each hot spot (initial data), and Automatic Vehicle Locator (AVL) (new) data on total patrol time within the Bgeo-fenced^area of each hot spot. The patrol measures were linked to two outcome measures at each hot spot. Part I crime reports and citizen-generated Calls for Service (CFS) records for events occurring within the hot spot street address boundaries. Methods All SHSE pairs of hot spots were examined as a meta-analysis of 21 experiments for differences in frequency and total duration of patrols. Then all 42 hot spots were examined for correlations between outcome measures and CAD data on frequency and duration, plus AVL data on duration [AVL data could not reliably measure frequency of discrete patrol visits]. Findings The SHSE created large mean differences between experimental and control conditions in both frequency and total duration of patrols, which were highly correlated (r = .9). Correlations of CAD measures of before-during increases in frequency, but not duration, of patrols across all 42 hot spots predicted somewhat fewer event counts of both outcome measures: crime reports (r = −.273, one-tailed p = .04) and CFS (r = −.234, one-tailed p = .068). In contrast, AVL data on before-during increases in duration showed somewhat less crime with more duration of total patrol time (r = −.231, one-tailed p = .07), but no effect of more duration on CFS. Conclusions Based on the analysis of CAD data, police may be able to reduce crime and disorder more effectively by making more frequent patrols in each hot spot, while reducing the total time of all patrols. Contrary to the policy conclusion from the Koper (1995) Curve, the CAD findings may suggest there is greater benefit in having more visits of under 15 min rather than having fewer visits that all last from 10 to 15 min each. Yet, the evidence from this study is mixed. The CAD finding is contradicted by this study's AVL data analysis, which show that greater increases in total patrol duration did predict somewhat fewer crimes (but not CFS). Since both the CAD and AVL findings are correlational rather than based on random assignment of frequency and duration, field experiments are now needed to provide more definitive answers to the research question.

‘Lowering the threshold of effective deterrence’—Testing the effect of private security agents in public spaces on crime: A randomized controlled trial in a mass transit system

“…We were more interested in behavioural adaptations, which result from a clearly-defined intervention. The ‘why’ question remains unanswered; we argue that security guards caused both crime reductions and detection of offenders, but we cannot describe the micro-mediation of the causal mechanism that plays part here [ 117 ]. Therefore, while we interpret the evidence to suggest that the threat of sanctions is causally related to crime prvention, we would like to see more research on decision-making processes—as we would recommend for all hot spots experiments more generally.…”

Sweet Spots for Hot Spots? A Cost-Effectiveness Comparison of Two Patrol Strategies

“…This contrasts sharply with the 1-year average of police presence for 15% of high-crime times (based on observers using stopwatches) that reduced crimes in 50 experimental hot spots in Minneapolis (Sherman and Weisburd 1995) compared to 50 control group hot spots that received only 7% of time with police presence. Even lower dosage of police presence was documented in the Sacramento (Mitchell 2017) and Birmingham city-centre (Williams and Coupe 2017) experiments. Thus, the far higher baseline levels of patrols in Liverpool than in previous experiments provide an ideal opportunity for careful testing of ways in which police resources might be re-directed to gang violence (see Carr et al 2017) or other crimes with higher aggregate levels of harm (Sherman et al 2016)-in order to reduce the overall level of crime harm in the community.…”

Policing Directions: A Systematic Review on the Effectiveness of Quantitative Police Presence

“…Apart from four studies (Schnelle et al 1977, Esbensen andTaylor 1984, Fritsch et 10 Due to the variety of effects examined, we use positive as an indication of desired outcome (i.e., statistical negative effect between police presence and reduction in crime, or statistical positive effect between police presence and trust in the police) 11 The here introduced categorization goes as follows: Very low: no mention of measurement, unclear basis for calculations Low: Staffing schedules, observations, hand written patrol logs Medium: Deployment data, Radio log and call data High: GPS tracking, experimental placement al. , Rosenfeld et al 2014, all studies state that police presence reduces crime (e.g., Koper 1995, Santos 2013, Rosenfeld et al 2014, Mitchell 2017, Weisburd et al 2017. As various hot spots experiments have stated (e.g., , Braga et al 2019a, Braga et al 2019b), crime can be reduced through focused police actions (Ratcliffe et al 2011, Taylor et al 2011.…”

“…Second, references from reviews that focused on police programs, police practices, and patrol strategies were consulted (Famega 2005, Bradford 2011, Lee et al 2013, Carriaga and Worrall 2015, Braga and Welsh 2016, Lee et al 2016, Chalfin and McCrary 2017, Braga et al 2019b, Braga et al 2019a, Braga et al 2019c, Kounadi et al 2020. Third, a cross-reference search was conducted on the preliminary selection to identify relevant publications, which were not yielded during the search (e.g., Thaler 1977, Richards et al 1985, Draca et al 2007, Hinkle and Weisburd 2008, Rosenfeld et al 2014, Blattman et al 2017, Mitchell 2017. Ultimately, three of the co-authors critically judged the final selection and one of the co-authors validated the deployed search strategies.…”

“…Myriad approaches and technologies exist to measure police presence: staffing schedules (e.g., Kelling et al 1974, Fritsch et al 1999, Andresen and Lau 2014, Ariel et al 2019, officer radio data (e.g., Kelling et al 1981, Santos 2013, Rosenfeld et al 2014, Schaefer et al 2019 or GPS data (e.g., Ariel et al 2016, Mitchell 2017, Williams and Coupe 2017, Davies and Bowers 2019. In controlled experimental trials, police presence can be set as an experimental condition and measuring might not be necessary, i.e., when a stationary police car is placed in the test area.…”